Technical Field
The present invention relates to a method of extracting an analyte from a sample using microwave-assisted headspace liquid-phase microextraction.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
The Arabian Gulf area has undergone tremendous changes over the past decades in relation to management of water resources. According to recent estimations, daily production of desalinated water in gulf countries reached up to 23 million cubic meters, and Saudi Arabia produces a lion's share of it, which is 11 million cubic meters [Roberts, D. A., et al., Impacts of Desalination Plant Discharges on the Marine Environment: A Critical Review of Published Studies. Water Res. 2010, 44, 5117-5128—incorporated herein by reference in its entirety]. The contaminants produced during the desalination have been extensively reported in the literature. Desalination contaminants have impacted the marine ecological environment, and as a result their detectable concentrations were found in phytoplankton, invertebrates, and fish [Roberts, D. A., et al., Impacts of Desalination Plant Discharges on the Marine Environment: A Critical Review of Published Studies. Water Res. 2010, 44, 5117-5128; Lattemann, S., et al., Environmental Impact and Impact Assessment of Seawater Desalination. Desalination 2008, 220, 1-15—each incorporated herein by reference in its entirety]. Massive losses of coral, plankton, and fish in the Hurghada region of the Red Sea have also been attributed to desalination discharges [Hashim A., et al., Impact of Desalination Plants Fluid Effluents on the Integrity of Seawater, with the Arabian Gulf in Perspective. Desalination 2005, 182, 373-393; Mabrook, B. Environmental Impact of Waste Brine Disposal of Desalination Plants, Red Sea, Egypt. Desalination 1994, 97, 453-465—each incorporated herein by reference in its entirety]. However, there exist only a few reports on the impact assessmentand bioaccumulation of disinfection byproducts in biota samples. For example, the Eastern Province of Saudi Arabia, where the world's largest water desalination plant is located, has not been evaluated to assess the impact of disinfection byproducts (DBPs) on biota. DBPs are unintentionally produced from the reactions of disinfectants with the natural organic matter in the water [Richardson, S. D., et al., Water Analysis: Emerging Contaminants and Current Issues. Anal. Chem. 2014, 86, 2813-2848—incorporated herein by reference in its entirety]. Many of the DBPs have been shown to cause cancer, and reproductive and developmental disorders in laboratory animals [Drinking Water Treatment, U.S. Environmental Protection Agency, EPA Document No. 810-F-99-013, Cincinnati, Ohio, 1999—incorporated herein by reference in its entirety]. They are also harmful to humans and are suspected carcinogens even at low parts per billion (ppb) concentration levels. Trihalomethanes (THMs) and haloketones (HKs) are among the most prevalent DBPs [Levesque, S., et al., Effects of Indoor Drinking Water Handling on Trihalomethanes and Haloacetic Acids. Water Res. 2006, 40, 2921-2930; Yang, X., et al., Factors Affecting Formation of Haloacetonitriles, Haloketones, Chloropicrin and Cyanogen Halides during Chloramination. Water Res. 2007, 41, 1193-1200—each incorporated herein by reference in its entirety]. For example, USEPA classified trichforomethane (TCM), bromodichloromethane (BDCM), and tribromomethane (TBM) as carcinogens, while chlorodibromomethane (CDBM) was listed as a possible carcinogen [Xu, X., et al., Percutaneous Absorption of Trihalomethanes, Haloacetic Acids, and Haloketones. Toxicol. Appl. Pharmacol. 2002, 184, 19-26—incorporated herein by reference in its entirety]. Some toxicological effects of HKs are also reported. More prominently, chromosornal aberrations are associated with trichloropropanone (TCP) [Blazak, W. F., et al., Activity of 1,1,1- and 1,1,3-Trichloroacetones in a Chromosomal Aberration Assay in CHO Cells and the Micronucleus and Spermhead Abnormality Assays in Mice. Mutat. Res. Toxicol. 1988, 206, 431-438—incorporated herein by reference in its entirety], and 1,1-dichloropropanone (DCP) has been reported to reduce cellular glutathione levels prior to cytotoxic effects [Merrick, B. A., et al., Chemical Reactivity, Cytotoxicity, and Mutagenicity of Chloropropanones. Toxicol. Appl. Pharmacol. 1987, 91, 46-54—incorporated herein by reference in its entirety]. Therefore, exposure to such compounds can lead to serious health implications.
The determination of various DBPs requires an efficient sample preparation method prior to chromatographic analyses. During the last two decades, different approaches of sample preparation have been reported for DBPs. Liquid-liquid extraction and solid phase extraction are commonly used conventional approaches [US Environmental Protection Agency. 1995 a Method 551.1: EPA-600/R-95/131. USEPA Office of Research and Development, National Exposure Research Laboratory, Cincinnati, Ohio; US Environmental Protection Agency. 2003 Method 552.3: USEPA Office of Ground Water and Drinking Water, Cincinnati, Ohio; Niri, V. H., et al., Fast Analysis of Volatile Organic Compounds and Disinfection by-Products in Drinking Water Using Solid-Phase Microextraction-Gas Chromatography/time-of-Flight Mass Spectrometry. J. Chromatogr. A 2008, 1201, 222-227—each incorporated herein by reference in its entirety]. These methods have many shortcomings, including consumption of large volumes of hazardous solvents, and furthermore, these time and labor-extensive extractions lead to low recoveries. Therefore, it is highly desirable to develop new extraction techniques for fast and accurate quantitation of trace level concentrations of DBPs in biological samples.
Microwave-assisted extraction (MAE) has a wide range of applications and overcomes many of the above-mentioned problems. It can be successfully applied to different biological samples such as plants and fish [Wang, S., et al., Design and Performance Evaluation of Ionic-Liquids-Based Microwave-Assisted Environmentally Friendly Extraction Technique for Camptothecin and 10-Hydroxycamptothecin from Samara of Camptotheca Acuminata. Ind. Eng. Chem. Res. 2011, 50, 13620-13627; Teo, C. C., et al., Development and Application of Microwave-Assisted Extraction Technique in Biological Sample Preparation for Small Molecule Analysis. Metabolomics 2013, 9, 1109-1128; Wang, H., et al., Dynamic Microwave-Assisted Extraction Coupled with Salting-out Liquid-Liquid Extraction for Determination of Steroid Hormones in Fish Tissues. J. Agric. Food Chem. 2012, 60, 10343-10351; Ma, Y., et al., Microwave-Assisted Extraction Combined with Gel Permeation Chromatography and Silica Gel Cleanup Followed by Gas Chromatography-Mass Spectrometry for the Determination of Organophosphorus Flame Retardants and Plasticizers in Biological Samples Anal. Chim. Acta 2013, 786, 47-53; Dong, S., et al., Four Different Methods Comparison for Extraction of Astaxanthin from Green Alga Haematococcus Pluvialis, ScientificWorldJournal. 2014, 2014, 1-7: Eskilsson, C. S., et al., Analytical-Scale Microwave-Assisted Extraction. J. Chromatogr. A 2000, 902, 227-250—each incorporated herein by reference in its entirety]. Minimizing the degradation of volatile and semi-volatile compounds, shortening the extraction time, lowering hazardous solvent consumption, and simplifying the entire operation are major advantages of MAE [Eskilsson, C. S., et al., Analytical-Scale Microwave-Assisted Extraction. J. Chromatogr. A 2000, 902, 227-250; Letelltei, M., et al., Influence of Sediment Grain Size on the Efficiency of Focused Microwave Extraction of Polycyclic Aromatic Hydrocarbons, Analyst 1999, 124, 5-14; Mandal, V., et al., Design and Performance Evaluation of a Microwave Based Low Carbon Yielding Extraction Technique for Naturally Occurring Bioactive Triterpenoid: Oleanolic Acid. Biochem. Eng. J. 2010, 50, 63-70; Ma, W., el al., Application of Ionic Liquids Based Microwave-Assisted Extraction of Three Alkaloids N-Nornuciferine, O-Nornuciferine, and Nuciferine from Lotus Leaf. Talanla 2010, 80, 1292-1297—each incorporated herein by reference in its entirety]. The combination of headspace extraction with MAE is an uncommon approach; however, to perform headspace extraction, instrumental modifications are required which makes it more tedious [Yeh, C.-H., et Headspace Solid-Phase Microextraction Analysis of Volatile Components in Phalaenopsis Nobby's Pacific Sunset. Molecules 2014, 19, 14080-14093—incorporated herein by reference in its entirety].
In view of the forgoing, one objective of the present disclosure is to provide a single step microwave-assisted headspace liquid-phase microextraction (MA-HS-LPME) method for the isolation and subsequent determination of analytes such as THMs and HKs in biota samples. In one aspect of this method, a PTFE ring is placed inside an extraction vial to support a solvent-containing porous membrane envelope or bag, and thus, no changes in the microwave instrument are required.